In fire alarm systems commonly used today, a central control panel communicates with many individual smoke sensors, reads their output level of smoke measurement, and uses software algorithms to determine if an alarm condition exists at any of the smoke sensors. The control panel may also incorporate programmed algorithms for example, to compensate for drift due to dust accumulation or other environmental factors.
The design of the detectors and the design of the algorithm are important factors in being able to quickly detect a true fire, while being able to resistant false fire indications. However, systems typically in use today do not take the states of other nearby detectors into account in making an alarm decision.
Another system less commonly used provides special multiple technology fire sensors. These special sensors include at least two different types of smoke, heat, or fire sensor technology in the same physical device.
A microcomputer is incorporated into each sensor. The microcomputer processes the multiple signals from the different types of sensors and provides a single signal to the control panel, which is a better measurement of fire than a single sensor. These multiple technology sensors typically do not take the measurements from other nearby sensors into account when making the alarm decision at one sensor location. The multiple sensors are also more expensive to manufacture than single sensors.
Thus, there continues to be a need for alarm systems which can cost-effectively and quickly determine the existence of an alarm condition while being resistant to false alarms. Preferably such systems could use single sensor-type detectors.